Transcript mb3ech13b - Chaparral Star Academy

Red = algae
Blue = indigestible
particles
Bivalves are particle selective (on gills in case of oyster
Crassostrea gigas); right shows ciliated tract where
particles accepted, left shows ones that are rejected.
Ward et al. 1997, Nature 390:131-132
Suspension Feeders
Sea squirt Styela montereyensis
Passive suspension feeding mechanism,
combined with active ciliary pump
Passive Suspension Feeders - Issues
Orientation in current
Current velocity - pressure
drag
Particle concentration saturation of feeding structure
(e.g., polyp processing)
Recap - Deposit Feeders and
Suspension Feeders
• Deposit Feeders - process particles on bottom
• Particles range from inorganic (e.g., sand grains)
to organic
• Organic range from indigestible (cellulose) to very
digestible (living digestible bacteria, microalgae)
• Quantity important (e.g., bacteria not sufficient as
food for most larger deposit feeders)
• Selectivity important, digestive strategies
important (type of digestion, throughput),
recycling of microalgae and external supply of
particles important (e.g., deposition after spring
phytoplankton bloom to bottom, deposition of
seaweed detritus)
Recap continued
• Suspension feeders - gather particles either
passively (protrude structure into current) or
actively(suck water into siphon)
• Suspension feeders have access different particle
qualities - clay, non-living organic matter,
microalgae of varying quality (some poisonous
some indigestible)
• Gathering of particles important, but selectivity
also important
• Digestive strategies and throughput also important
issues
• Flow very important - causes change in form
Carnivores
Oystercatcher
Gastropod Nucella
Bivalve Cuspidaria
Polychaete
Glycera
Crab Callinectes sapidus
Carnivore Issues
• Low population size, movement to patches
of prey
• Capture of prey
• Physiological limitations (depth of
swimming, sensory biology, intertidal zone)
• Feeding, while avoiding predation by other
species
Conus, over 500 spp. mainly in coral reefs
Poison: cysteine-rich peptides - attack ion channels, each
species has many different peptides
Conus geographus
Conus striatus
C. striatus
C. geographus
Diversity of poisonous peptides arise with evolution of
multiple gene families, result from gene duplications and later
divergence of toxic function
Herbivores
Polychaete Nereis vexillosa
Parrot fish
radula
Chiton
Urchins
Herbivore Issues
• Ability to mechanically attack plants
• Chemical defense of plants
• Feeding, while avoiding predation by other
species
Cellulose Feeder
Obtains nitrogen with symbiotic nitrogen fixing bacteria
The End